Brighton and Hove's Green Party also issued a statement an hour after Mr Duncan's apology which said: "Councillor Ben

Duncan's remarks were deeply offensive and unacceptable. We have asked him to make an immediate apology, which he has."

While Ms Lucas said: "I think it's deeply offensive and have told him so, and have asked him to apologise."

Green council leader Jason Kitcat was also quick to condemn Mr Duncan's comment. When asked if he agreed with his fellow councillor, he said: "Absolutely not. It's a disgraceful and offensive tweet."

But those who have read Mr Duncan's tweets said his apology was "too little, too late" and have set up a petition demanding his resignation.

Labour councillor Warren Morgan said: "Councillor Duncan should resign and he should do so quickly.

"He is free to criticise politicians who send troops to war, but not those who risk and often sacrifice their lives as a consequence.

"His comments are stupid and deeply offensive, particularly when we are marking the anniversaries of D-Day and World War One.

"Were he a councillor in my group he would be gone by the end of the day. However, based on past experience the Green Party will do nothing."

Former council leader Lord Bassam tweeted: "This is offensive. My mother's brother died aged 21 fighting Nazi's so you can enjoy freedom of speech.. please reflect on that."

Political blogger Guido Fawkes also tweeted: "Last tweet from Brighton Green councillor. He should tell his son they risk their lives for his freedom of speech."

It is not the first time Mr Duncan has courted controversy for making inappropriate comments.

In May 2012, The Argus newspaper reported that he was forced to apologise during a debate on legalised cannabis cafes when he tweeted: "I only smoke weed when I'm murdering, raping and looting!"

He later apologised through his blog for mentioning rape in what he claimed was meant to be "a light-hearted, ironic tweet".

Earlier this year Tory councillor Mary Mears lodged a formal complaint after Mr Duncan accused her of wearing a swastika necklace at a meeting in March, the Brighton Argus reported.

Mrs Mears told the paper she had been wearing a St Brigid's cross, the symbol of St Brigid of Kildare, one of the patron saints of Ireland.

Mr Duncan has been ordered to apologise again for the incident at a full council meeting next month after a report to the council's Audit and Standards Committee said his apology at the meeting in March was "not taken as sincere".